Portable fuel processor

ABSTRACT

Described herein is a fuel processor that produces hydrogen from a fuel source. The fuel processor comprises a reformer and burner. The reformer includes a catalyst that facilitates the production of hydrogen from the fuel source. Voluminous reformer chamber designs are provided that increase the amount of catalyst that can be used in a reformer and increase hydrogen output for a given fuel processor size. The burner provides heat to the reformer. One or more burners may be configured to surround a reformer on multiple sides to increase thermal transfer to the reformer. Dewars are also described that increase thermal management of a fuel processor and increase burner efficiency. A dewar includes one or more dewar chambers that receive inlet air before a burner receives the air. The dewar is arranged such that air passing through the dewar chamber intercepts heat generated in the burner before the heat escapes the fuel processor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation and claims priority under 35 U.S.C.§120 from co-pending U.S. patent application Ser. No. 11/772,689, filedJul. 2, 2007 and entitled, “PORTABLE FUEL PROCESSOR,” which is acontinuation and claims priority under 35 U.S.C. §120 from U.S. patentapplication Ser. No. 10/877,044, filed Jun. 25, 2004 and entitled,“ANNULAR FUEL PROCESSOR AND METHODS,” now U.S. Pat. No. 7,604,673, whichis incorporated herein for all purposes; the Ser. No. 10/877,044 patentapplication claimed priority under 35 U.S.C. §119(e) from U.S.Provisional Patent Application No. 60/482,996 entitled “FUEL CELL SYSTEMSTARTUP PROCEDURE AND SELF-HEATING APPARATUS,” filed Jun. 27, 2003 whichis incorporated by reference for all purposes; the 10/877,044 PatentApplication also claimed priority under 35 U.S.C. §119(e) from U.S.Provisional Patent Application No. 60/483,416 entitled “FUEL PREHEAT INPORTABLE ELECTRONICS POWERED BY FUEL CELLS,” filed Jun. 27, 2003, whichis incorporated by reference for all purposes.

BACKGROUND OF THE INVENTION

The present invention relates to fuel cell technology. In particular,the invention relates to fuel processors that generate hydrogen and aresuitable for use in portable applications.

A fuel cell electrochemically combines hydrogen and oxygen to produceelectricity. The ambient air readily supplies oxygen. Hydrogenprovision, however, calls for a working supply. Gaseous hydrogen has alow energy density that reduces its practicality as a portable fuel.Liquid hydrogen, which has a suitable energy density, must be stored atextremely low temperatures and high pressures, making storing andtransporting liquid hydrogen burdensome.

A reformed hydrogen supply processes a fuel source to produce hydrogen.The fuel source acts as a hydrogen carrier. Currently availablehydrocarbon fuel sources include methanol, ethanol, gasoline, propaneand natural gas. Liquid hydrocarbon fuel sources offer high energydensities and the ability to be readily stored and transported. A fuelprocessor reforms the hydrocarbon fuel source and to produce hydrogen.

Fuel cell evolution so far has concentrated on large-scale applicationssuch as industrial size generators for electrical power back-up.Consumer electronics devices and other portable electrical powerapplications currently rely on lithium ion and similar batterytechnologies. Fuel processors for portable applications such aselectronics would be desirable but are not yet commercially available.In addition, techniques that reduce fuel processor size or increase fuelprocessor efficiency would be highly beneficial.

SUMMARY OF THE INVENTION

The present invention relates to a fuel processor that produces hydrogenfrom a fuel source. The fuel processor comprises a reformer and burner.The reformer includes a catalyst that facilitates the production ofhydrogen from the fuel source. Voluminous reformer chamber designs areprovided that increase the amount of catalyst that can be used in areformer and increase hydrogen output for a given fuel processor size.The burner provides heat to the reformer. One or more burners may beconfigured to surround a reformer on multiple sides to increase thermaltransfer to the reformer.

Dewars are also described that improve thermal management of a fuelprocessor by reducing heat loss and increasing burner efficiency. Adewar includes one or more dewar chambers that receive inlet processgases or liquids before a reactor receives them. The dewar is arrangedsuch that inlet process gases or liquids passing through the dewarchamber intercepts heat generated in the burner before the heat escapesthe fuel processor. Passing inlet process gases or liquids through adewar chamber in this manner performs three functions: a) active coolingof dissipation of heat generated in burner before is reaches outerportions of the fuel processor, and b) heating of the air before receiptby the burner, and c) absorbing and recycling heat back into the burnerincreasing burner efficiency. When the burner relies on catalyticcombustion to produce heat, heat generated in the burner warms coolprocess gases or liquids in the burner according to the temperature ofthe process gases or liquids. This steals heat from the reformer,reduces heating efficiency of a burner and typically results in greaterconsumption of the fuel source. The dewar thus pre-heats the incomingprocess gases or liquids before burner arrival so the burner passes lessheat to the process gases or liquids that would otherwise transfer tothe reformer.

In one aspect, the present invention relates to a fuel processor forproducing hydrogen from a fuel source. The fuel processor comprises areformer configured to receive the fuel source, configured to outputhydrogen, and including a catalyst that facilitates the production ofhydrogen. The fuel processor also comprises a boiler configured to heatthe fuel source before the reformer receives the fuel source. The fuelprocessor further comprises at least one burner configured to provideheat to the reformer and disposed annularly about the reformer. The fuelprocessor may also comprise a boiler that heats the burner liquid fuelfeed.

In another aspect, the present invention relates to a fuel processor forproducing hydrogen from a fuel source. The fuel processor comprises areformer configured to receive the fuel source, configured to outputhydrogen, including a catalyst that facilitates the production ofhydrogen. The reformer also includes a reformer chamber having a volumegreater than about 0.1 cubic centimeters and less than about 50 cubiccentimeters and is characterized by a cross sectional width and a crosssectional height that is greater than one-third the cross sectionalwidth. The fuel processor also comprises a boiler configured to heat thefuel source before the reformer receives the fuel source. The fuelprocessor further comprises at least one burner configured to provideheat to the reformer.

In yet another aspect, the present invention relates to a fuel processorfor producing hydrogen from a fuel source. The fuel processor comprisesa reformer configured to receive the hydrogen fuel source, configured tooutput hydrogen, and including a catalyst that facilitates theproduction of hydrogen. The fuel processor also comprises a burner thatis configured to provide heat to the reformer. The fuel processorfurther comprises a dewar that at least partially contains the reformerand the burner and includes a set of dewar walls that form a dewarchamber that is configured to receive an inlet process gas or liquidbefore the burner receives the inlet process gas or liquid. The fuelprocessor additionally comprises a housing including a set of housingwalls that at least partially contain the dewar and provide externalmechanical protection for the reformer and the burner.

In still another aspect, the present invention relates to a method formanaging heat in a fuel processor. The fuel processor comprises aburner, a reformer and a dewar that at least partially contains theburner. The method comprises generating heat in the burner. The methodalso comprises passing an inlet process gas or liquid through a dewarchamber. The method further comprises heating the inlet process gas orliquid in the dewar chamber using heat generated in the burner.

In another aspect, the present invention relates to a method forgenerating hydrogen in a fuel processor. The fuel processor comprises aburner, a reformer and a dewar that at least partially contains theburner and reformer. The method comprises generating heat in the burner.The method also comprises passing an inlet process gas or liquid througha dewar chamber. The method further comprises heating the inlet processgas or liquid in the dewar chamber using heat generated in the burner.The method additionally comprises supplying the inlet process gas orliquid to the burner after it has been heated in the dewar chamber. Themethod also comprises transferring heat generated in the burner to thereformer. The method further comprises reforming a fuel source toproduce hydrogen.

These and other features and advantages of the present invention will bedescribed in the following description of the invention and associatedfigures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a fuel cell system for producing electrical energyin accordance with one embodiment of the present invention.

FIG. 1B illustrates schematic operation for the fuel cell system of FIG.1A in accordance with a specific embodiment of the present invention.

FIG. 1C illustrates an embodiment of the fuel cell system of FIG. 1Athat routes hydrogen from an anode exhaust of the fuel cell back to aburner in the fuel processor.

FIG. 2A illustrates a cross-sectional side view of a fuel processor usedin the fuel cell system of FIG. 1A in accordance with one embodiment ofthe present invention.

FIG. 2B illustrates a cross-sectional front view of the fuel processorused in the fuel cell system of FIG. 1A taken through a mid-plane offuel processor.

FIG. 3A illustrates a cross-sectional front view of a monolithicstructure employed in the fuel processor of FIG. 2A in accordance withone embodiment of the present invention.

FIG. 3B illustrates a cross-sectional layout of a tubular design for usein a fuel processor in accordance with another embodiment of the presentinvention.

FIG. 3C illustrates a cross-sectional front view of a monolithicstructure in a fuel processor that comprises a single burner having an‘O-shape’ that completely surrounds a reformer chamber in accordancewith one embodiment of the present invention.

FIG. 3D illustrates an outside view of an end plate used in the fuelprocessor of FIG. 2A.

FIG. 3E illustrates a fuel processor 15 in accordance with anotherembodiment of the present invention.

FIG. 4A illustrates a side cross-sectional view of the fuel processor ofFIG. 2A and movement of air created by a dewar in accordance with oneembodiment of the present invention.

FIG. 4B illustrates a front cross-sectional view of the fuel processorof FIG. 2A and demonstrates thermal management benefits gained by thedewar.

FIG. 4C shows a thermal diagram of the heat path produced by a dewarwall used in the fuel processor of FIG. 2A.

FIG. 4D illustrates a cross sectional view of a fuel processor thatincreases the convective path that air flows over a dewar wall inaccordance with another embodiment of the present invention.

FIG. 4E illustrates a dewar in accordance with another embodiment of thepresent invention.

FIGS. 4F and 4G illustrate a cross section of a fuel processor includinga monolithic structure and multipass dewar in accordance with anotherembodiment of the present invention.

FIG. 4H illustrates spiral dewar in an unrolled form during initialconstruction in accordance with another embodiment of the presentinvention.

FIGS. 4I and 4J illustrate wash coatings on a wall of a burner inaccordance with two embodiments of the present invention.

FIG. 5 illustrates a process flow for generating hydrogen in a fuelprocessor in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is described in detail with reference to a fewpreferred embodiments as illustrated in the accompanying drawings. Inthe following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention. Itwill be apparent, however, to one skilled in the art, that the presentinvention may be practiced without some or all of these specificdetails. In other instances, well known process steps and/or structureshave not been described in detail in order to not unnecessarily obscurethe present invention.

FIG. 1A illustrates a fuel cell system 10 for producing electricalenergy in accordance with one embodiment of the present invention. Fuelcell system 10 comprises storage device 16, fuel processor 15 and fuelcell 20.

A ‘reformed’ hydrogen supply processes a fuel source to producehydrogen. As shown, the reformed hydrogen supply comprises a fuelprocessor 15 and a fuel source storage device 16. Storage device 16stores fuel source 17, and may include a portable and/or disposable fuelcartridge. A disposable cartridge offers instant recharging to aconsumer. In one embodiment, the cartridge includes a collapsiblebladder within a hard plastic dispenser case. A separate fuel pumptypically controls fuel source 17 flow from storage device 16. If system10 is load following, then a control system meters fuel source 17 todeliver fuel source 17 to processor 15 at a flow rate determined by therequired power level output of fuel cell 20.

Fuel source 17 acts as a carrier for hydrogen and can be processed toseparate hydrogen. Fuel source 17 may include any hydrogen bearing fuelstream, hydrocarbon fuel or other hydrogen fuel source such as ammonia.Currently available hydrocarbon fuel sources 17 suitable for use withthe present invention include gasoline, C₁ to C₄ hydrocarbons, theiroxygenated analogues and/or their combinations, for example. Severalhydrocarbon and ammonia products may also produce a suitable fuel source17. Liquid fuel sources 17 offer high energy densities and the abilityto be readily stored and shipped. Storage device 16 may contain a fuelmixture. When the fuel processor 15 comprises a steam reformer, storagedevice 16 may contain a fuel mixture of a hydrocarbon fuel source andwater. Hydrocarbon fuel source/water fuel mixtures are frequentlyrepresented as a percentage fuel source in water. In one embodiment,fuel source 17 comprises methanol or ethanol concentrations in water inthe range of 1%-99.9%. Other liquid fuels such as butane, propane,gasoline, military grade “JP8” etc. may also be contained in storagedevice 16 with concentrations in water from 5-100%. In a specificembodiment, fuel source 17 comprises 67% methanol by volume.

Fuel processor 15 processes the hydrocarbon fuel source 17 and outputshydrogen. A hydrocarbon fuel processor 15 heats and processes ahydrocarbon fuel source 17 in the presence of a catalyst to producehydrogen. Fuel processor 15 comprises a reformer, which is a catalyticdevice that converts a liquid or gaseous hydrocarbon fuel source 17 intohydrogen and carbon dioxide. As the term is used herein, reformingrefers to the process of producing hydrogen from a fuel source. Fuelprocessor 15 may output either pure hydrogen or a hydrogen bearing gasstream. Fuel processor 15 is described in further detail below.

Fuel cell 20 electrochemically converts hydrogen and oxygen to water,generating electricity and heat in the process. Ambient air commonlysupplies oxygen for fuel cell 20. A pure or direct oxygen source mayalso be used for oxygen supply. The water often forms as a vapor,depending on the temperature of fuel cell 20 components. Theelectrochemical reaction also produces carbon dioxide as a byproduct formany fuel cells.

In one embodiment, fuel cell 20 is a low volume polymer electrolytemembrane (PEM) fuel cell suitable for use with portable applicationssuch as consumer electronics. A polymer electrolyte membrane fuel cellcomprises a membrane electrode assembly 40 that carries out theelectrical energy generating electrochemical reaction. The membraneelectrode assembly 40 includes a hydrogen catalyst, an oxygen catalystand an ion conductive membrane that a) selectively conducts protons andb) electrically isolates the hydrogen catalyst from the oxygen catalyst.A hydrogen gas distribution layer contains the hydrogen catalyst andallows the diffusion of hydrogen therethrough. An oxygen gasdistribution layer contains the oxygen catalyst and allows the diffusionof oxygen and hydrogen protons therethrough. The ion conductive membraneseparates the hydrogen and oxygen gas distribution layers. In chemicalterms, the anode comprises the hydrogen gas distribution layer andhydrogen catalyst, while the cathode comprises the oxygen gasdistribution layer and oxygen catalyst.

A PEM fuel cell often includes a fuel cell stack having a set ofbi-polar plates. A membrane electrode assembly is disposed between twobi-polar plates. Hydrogen distribution 43 occurs via a channel field onone plate while oxygen distribution 45 occurs via a channel field on asecond facing plate. Specifically, a first channel field distributeshydrogen to the hydrogen gas distribution layer, while a second channelfield distributes oxygen to the oxygen gas distribution layer. The ‘term‘bi-polar’ refers electrically to a bi-polar plate (whether comprised ofone plate or two plates) sandwiched between two membrane electrodeassembly layers. In this case, the bi-polar plate acts as both anegative terminal for one adjacent membrane electrode assembly and apositive terminal for a second adjacent membrane electrode assemblyarranged on the opposite face of the bi-polar plate.

In electrical terms, the anode includes the hydrogen gas distributionlayer, hydrogen catalyst and bi-polar plate. The anode acts as thenegative electrode for fuel cell 20 and conducts electrons that arefreed from hydrogen molecules so that they can be used externally, e.g.,to power an external circuit. In a fuel cell stack, the bi-polar platesare connected in series to add the potential gained in each layer of thestack. In electrical terms, the cathode includes the oxygen gasdistribution layer, oxygen catalyst and bi-polar plate. The cathoderepresents the positive electrode for fuel cell 20 and conducts theelectrons back from the external electrical circuit to the oxygencatalyst, where they can recombine with hydrogen ions and oxygen to formwater.

The hydrogen catalyst separates the hydrogen into protons and electrons.The ion conductive membrane blocks the electrons, and electricallyisolates the chemical anode (hydrogen gas distribution layer andhydrogen catalyst) from the chemical cathode. The ion conductivemembrane also selectively conducts positively charged ions.Electrically, the anode conducts electrons to a load (electricity isproduced) or battery (energy is stored). Meanwhile, protons move throughthe ion conductive membrane, to combine with oxygen. The protons andused electrons subsequently meet on the cathode side, and combine withoxygen to form water. The oxygen catalyst in the oxygen gas distributionlayer facilitates this reaction. One common oxygen catalyst comprisesplatinum powder very thinly coated onto a carbon paper or cloth. Manydesigns employ a rough and porous catalyst to increase surface area ofthe platinum exposed to the hydrogen and oxygen.

In one embodiment, fuel cell 20 comprises a set of bi-polar plates thateach includes channel fields on opposite faces that distribute thehydrogen and oxygen. One channel field distributes hydrogen while achannel field on the opposite face distributes oxygen. Multiple bi-polarplates can be stacked to produce a ‘fuel cell stack’ in which a membraneelectrode assembly is disposed between each pair of adjacent bi-polarplates. Since the electrical generation process in fuel cell 20 isexothermic, fuel cell 20 may implement a thermal management system todissipate heat from the fuel cell. Fuel cell 20 may also employ a numberof humidification plates (HP) to manage moisture levels in the fuelcell. Further description of a fuel cell suitable for use with thepresent invention is included in commonly owned co-pending patentapplication entitled “Micro Fuel Cell Architecture” naming Ian Kaye asinventor and filed on the same day as this patent application. Thisapplication is incorporated by reference for all purposes.

While the present invention will mainly be discussed with respect to PEMfuel cells, it is understood that the present invention may be practicedwith other fuel cell architectures. The main difference between fuelcell architectures is the type of ion conductive membrane used. In oneembodiment, fuel cell 20 is phosphoric acid fuel cell that employsliquid phosphoric acid for ion exchange. Solid oxide fuel cells employ ahard, non-porous ceramic compound for ion exchange and may be suitablefor use with the present invention. Generally, any fuel cellarchitecture may benefit from fuel processor improvements describedherein. Other such fuel cell architectures include direct methanol,alkaline and molten carbonate fuel cells.

Fuel cell 20 generates dc voltage that may be used in a wide variety ofapplications. For example, electricity generated by fuel cell 20 may beused to power a motor or light. In one embodiment, the present inventionprovides ‘small’ fuel cells that are designed to output less than 200watts of power (net or total). Fuel cells of this size are commonlyreferred to as ‘micro fuel cells’ and are well suited for use withportable electronics. In one embodiment, fuel cell 20 is configured togenerate from about 1 milliwatt to about 200 watts. In anotherembodiment, fuel cell 20 generates from about 3 W to about 20 W. Fuelcell 20 may also be a stand-alone fuel cell, which is a single unit thatproduces power as long as it has an a) oxygen and b) hydrogen or ahydrocarbon fuel supply. A fuel cell 20 that outputs from about 40W toabout 100W is well suited to power a laptop computer.

FIG. 1B illustrates schematic operation for fuel cell system 10 inaccordance with a specific embodiment of the present invention. Asshown, fuel cell system 10 comprises fuel container 16, hydrogen fuelsource 17, fuel processor 15, fuel cell 20, multiple pumps 21 and fans35, fuel lines and gas lines, and one or more valves 23. While thepresent invention will now primarily be described with respect tomethanol as fuel source 17, it is understood that the present inventionmay employ another fuel source 17 such as one provided above.

Fuel container 16 stores methanol as a hydrogen fuel source 17. Anoutlet 26 of fuel container 16 provides methanol 17 into hydrogen fuelsource line 25. As shown, line 25 divides into two lines: a first line27 that transports methanol 17 to a burner 30 for fuel processor 15 anda second line 29 that transports methanol 17 to reformer 32 in fuelprocessor 15. Lines 25, 27 and 29 may comprise plastic tubing, forexample. Separate pumps 21 a and 21 b are provided for lines 27 and 29,respectively, to pressurize the lines and transmit the fuel source atindependent rates if desired. A model P625 pump as provided by Instechof Plymouth Meeting, Pa. is suitable to transmit liquid methanol forsystem 10 is suitable in this embodiment. A flow sensor or valve 23situated on line 29 between storage device 16 and fuel processor 18detects and communicates the amount of methanol 17 transfer betweenstorage device 16 and reformer 32. In conjunction with the sensor orvalve 23 and suitable control, such as digital control applied by aprocessor that implements instructions from stored software, pump 21 bregulates methanol 17 provision from storage device 16 to reformer 32.

Fan 35 a delivers oxygen and air from the ambient room through line 31to regenerator 36 of fuel processor 15. Fan 35 b delivers oxygen and airfrom the ambient room through line 33 to regenerator 36 of fuelprocessor 15. In this embodiment, a model AD2005DX-K70 fan as providedby Adda USA of California is suitable to transmit oxygen and air forfuel cell system 10. A fan 37 blows cooling air over fuel cell 20 andits heat transfer appendages 46.

Fuel processor 15 receives methanol 17 from storage device 16 andoutputs hydrogen. Fuel processor 15 comprises burner 30, reformer 32,boiler 34 and dewar 150. Burner 30 includes an inlet that receivesmethanol 17 from line 27 and a catalyst that generates heat withmethanol presence. In one embodiment, burner 30 includes an outlet thatexhausts heated gases to a line 41, which transmits the heated gasesover heat transfer appendages 46 of fuel cell 20 to pre-heat the fuelcell and expedite warm-up time needed when initially turning on fuelcell 20. An outlet of burner 30 may also exhaust heated gases into theambient room.

Boiler 34 includes an inlet that receives methanol 17 from line 29. Thestructure of boiler 34 permits heat produced in burner 30 to heatmethanol 17 in boiler 34 before reformer 32 receives the methanol 17.Boiler 34 includes an outlet that provides heated methanol 17 toreformer 32.

Reformer 32 includes an inlet that receives heated methanol 17 fromboiler 34. A catalyst in reformer 32 reacts with the methanol 17 andproduces hydrogen and carbon dioxide. This reaction is slightlyendothermic and draws heat from burner 30. A hydrogen outlet of reformer32 outputs hydrogen to line 39. In one embodiment, fuel processor 15also includes a preferential oxidizer that intercepts reformer 32hydrogen exhaust and decreases the amount of carbon monoxide in theexhaust. The preferential oxidizer employs oxygen from an air inlet tothe preferential oxidizer and a catalyst based on, for example rutheniumor platinum, that is preferential to carbon monoxide over carbondioxide.

Dewar 150 pre-heats a process gas or liquid before the air enters burner30. Dewar 150 also reduces heat loss from fuel cell 15 by heating theincoming process liquids or gases before the heat escapes fuel processor15. In one sense, dewar 150 acts as a regenerator that uses waste heatin fuel processor 15 to improve thermal management and thermalefficiency of the fuel processor. Specifically, waste heat from burner30 may be used to pre-heat incoming air provided to burner 30 to reduceheat transfer to the air in the burner so more heat transfers toreformer 32. Dewar 150 is described in further detail below.

Line 39 transports hydrogen from fuel processor 15 to fuel cell 20.Gaseous delivery lines 31, 33 and 39 may comprise polymeric or metallictubing, for example. A hydrogen flow sensor (not shown) may also beadded on line 39 to detect and communicate the amount of hydrogen beingdelivered to fuel cell 20. In conjunction with the hydrogen flow sensorand suitable control, such as digital control applied by a processorthat implements instructions from stored software, fuel processor 15regulates hydrogen gas provision to fuel cell 20.

Fuel cell 20 includes an hydrogen inlet port that receives hydrogen fromline 39 and delivers it to a hydrogen intake manifold for delivery toone or more bi-polar plates and their hydrogen distribution channels. Anoxygen inlet port of fuel cell 20 receives oxygen from line 33 anddelivers it to an oxygen intake manifold for delivery to one or morebi-polar plates and their oxygen distribution channels. An anode exhaustmanifold collects gases from the hydrogen distribution channels anddelivers them to an anode exhaust port, which outlets the exhaust gasesinto the ambient room. A cathode exhaust manifold collects gases fromthe oxygen distribution channels and delivers them to a cathode exhaustport.

The schematic operation for fuel cell system 10 shown in FIG. 1B isexemplary and other variations on fuel cell system design, such asreactant and byproduct plumbing, are contemplated. In addition to thecomponents shown in shown in FIG. 1B, system 10 may also include otherelements such as electronic controls, additional pumps and valves, addedsystem sensors, manifolds, heat exchangers and electrical interconnectsuseful for carrying out functionality of system 10 that are known to oneof skill in the art and omitted herein for sake of brevity.

FIG. 1C illustrates an embodiment of fuel system 10 that routes unusedhydrogen from fuel cell 20 back to burner 30. Burner 30 includes acatalyst that reacts with the unused hydrogen to produce heat. Sincehydrogen consumption within fuel cell 20 is often incomplete and theanode exhaust often includes unused hydrogen, re-routing the anodeexhaust to burner 30 allows fuel cell system 10 to capitalize on unusedhydrogen in fuel cell 20 and increase hydrogen usage and efficiency insystem 10. As the term is used herein, unused hydrogen generally refersto hydrogen output from a fuel cell.

Line 51 is configured to transmit unused hydrogen from fuel cell 20 toburner 30 of fuel processor 15. For FIG. 1C, burner 30 includes twoinlets: an inlet 55 configured to receive the hydrogen fuel source 17and an inlet 53 configured to receive the hydrogen from line 51. Anodegas collection channels, which distribute hydrogen from fuel processor15 to each membrane electrode assembly layer, collect and exhaust theunused hydrogen. An inlet fan pressurizes line 39 that delivers thehydrogen from an outlet of fuel processor 15 to an anode inlet of fuelcell 20. The inlet fan also pressurizes the anode gas collectionchannels for distribution of hydrogen within fuel cell 20. In oneembodiment, gaseous delivery in line 51 back to fuel processor 15 relieson pressure at the exhaust of the anode gas distribution channels, e.g.,in the anode exhaust manifold. In another embodiment, an extra fan isadded to line 51 to pressurize line 51 and return unused hydrogen backto fuel processor 15.

Burner 30 also includes an inlet 59 configured to receive oxygen from anoxygen exhaust included in fuel cell 20. Cathode gas collectionchannels, which distribute oxygen and air from the ambient room to eachmembrane electrode assembly layer, collect and exhaust the unusedoxygen. Line 61 delivers unused oxygen from an exhaust manifold, whichcollects oxygen from each cathode gas collection channel, to inlet 59.Burner 30 thus includes two oxygen inlets: inlet 59 and an inlet 57configured to receive oxygen from the ambient room after delivery thoughdewar 150. Since oxygen consumption within fuel cell 20 is oftenincomplete and the cathode exhaust includes unused oxygen, re-routingthe cathode exhaust to burner 30 allows fuel cell system 10 tocapitalize on unused oxygen in fuel cell 20 and increase oxygen usageand efficiency in system 10.

In one embodiment, fuel processor 15 is a steam reformer that only needssteam to produce hydrogen. Several types of reformers suitable for usein fuel cell system 10 include steam reformers, auto thermal reformers(ATR) or catalytic partial oxidizers (CPDX). ATR and CPDX reformers mixair with the fuel and steam mix. ATR and CPDX systems reform fuels suchas methanol, diesel, regular unleaded gasoline and other hydrocarbons.In a specific embodiment, storage device 16 provides methanol 17 to fuelprocessor 15, which reforms the methanol at about 250° C. or less andallows fuel cell system 10 use in applications where temperature is tobe minimized.

FIG. 2A illustrates a cross-sectional side view of fuel processor 15 inaccordance with one embodiment of the present invention. FIG. 2Billustrates a cross-sectional front view of fuel processor 15 takenthrough a mid-plane of processor 15 that also shows features of endplate 82. Fuel processor 15 reforms methanol to produce hydrogen. Fuelprocessor 15 comprises monolithic structure 100, end plates 82 and 84,reformer 32, burner 30, boiler 34, boiler 108, dewar 150 and housing152. Although the present invention will now be described with respectto methanol consumption for hydrogen production, it is understood thatfuel processors of the present invention may consume another fuelsource, as one of skill in the art will appreciate.

As the term is used herein, ‘monolithic’ refers to a single andintegrated structure that includes at least portions of multiplecomponents used in fuel processor 15. As shown, monolithic structure 100includes reformer 32, burner 30, boiler 34 and boiler 108. Monolithicstructure 100 may also include associated plumbing inlets and outletsfor reformer 32, burner 30 and boiler 34. Monolithic structure 100comprises a common material 141 that constitutes the structure. Commonmaterial 141 is included in walls that define the reformer 32, burner 32and boilers 34 and 108. Specifically, walls 111, 119, 120, 122, 130,132, 134 and 136 all comprise common material 141. Common material 141may comprise a metal, such as copper, silicon, stainless steel, inconeland other metal/alloys displaying favorable thermal conductingproperties. The monolithic structure 100 and common material 141simplify manufacture of fuel processor 15. For example, using a metalfor common material 141 allows monolithic structure 100 to be formed byextrusion or casting. In some cases, monolithic structure 100 isconsistent in cross sectional dimensions between end plates 82 and 84and solely comprises copper formed in a single extrusion. Commonmaterial 141 may also include a ceramic, for example. A ceramicmonolithic structure 100 may be formed by sintering.

Housing 152 provides mechanical protection for internal components offuel processor 15 such as burner 30 and reformer 32. Housing 152 alsoprovides separation from the environment external to processor 15 andincludes inlet and outlet ports for gaseous and liquid communication inand out of fuel processor 15. Housing 152 includes a set of housingwalls 161 that at least partially contain a dewar 150 and provideexternal mechanical protection for components in fuel processor 15.Walls 161 may comprises a suitably stiff material such as a metal or arigid polymer, for example. Dewar 150 improves thermal heat managementfor fuel processor 15 and will be discussed in further detail withrespect to FIG. 4A.

Together, monolithic structure 100 and end plates 82 and 84 structurallydefine reformer 32, burner 30, boiler 34 and boiler 108 and theirrespective chambers. Monolithic structure 100 and end plates 82 and 84are shown separate in FIG. 2A for illustrative purposes, while FIG. 4Ashows them together.

Referring to FIG. 2B, boiler 34 heats methanol before reformer 32receives the methanol. Boiler 34 receives the methanol via fuel sourceinlet 81, which couples to the methanol supply line 27 of FIG. 1B. Sincemethanol reforming and hydrogen production via a catalyst 102 inreformer 32 often requires elevated methanol temperatures, fuelprocessor 15 pre-heats the methanol before receipt by reformer 32 viaboiler 34. Boiler 34 is disposed in proximity to burner 30 to receiveheat generated in burner 30. The heat transfers via conduction throughmonolithic structure from burner 30 to boiler 34 and via convection fromboiler 34 walls to the methanol passing therethrough. In one embodiment,boiler 34 is configured to vaporize liquid methanol. Boiler 34 thenpasses the gaseous methanol to reformer 32 for gaseous interaction withcatalyst 102.

Reformer 32 is configured to receive methanol from boiler 34. Walls 111in monolithic structure 100 (see cross section in FIG. 3A) and end walls113 (FIG. 2B) on end plates 82 and 84 define dimensions for a reformerchamber 103. In one embodiment, end plate 82 and/or end plate 84includes also channels 95 (FIG. 2A) that route heated methanol exhaustedfrom boiler 34 into reformer 32. The heated methanol then enters thereformer chamber 103 at one end of monolithic structure 100 and passesto the other end where the reformer exhaust is disposed. In anotherembodiment, a hole disposed in a reformer 32 wall receives inlet heatedmethanol from a line or other supply. The inlet hole or port may bedisposed on a suitable wall 111 or 113 of reformer 32.

Reformer 32 includes a catalyst 102 that facilitates the production ofhydrogen. Catalyst 102 reacts with methanol 17 and facilitates theproduction of hydrogen gas and carbon dioxide. In one embodiment,catalyst 102 comprises pellets packed to form a porous bed or otherwisesuitably filled into the volume of reformer chamber 103. In oneembodiment, pellet sizes are designed to maximize the amount of surfacearea exposure to the incoming methanol. Pellet diameters ranging fromabout 50 microns to about 1.5 millimeters are suitable for manyapplications. Pellet diameters ranging from about 300 microns to about1500 microns are suitable for use with reformer chamber 103. Pelletsizes and packing may also be varied to control the pressure drop thatoccurs through reformer chamber 103. In one embodiment, pressure dropsfrom about 0.2 to about 5 psi gauge are suitable between the inlet andoutlet of reformer chamber 103. Pellet sizes may be varied relative tothe cross sectional size of reformer chamber 103, e.g., as reformerchamber 103 increases in size so may catalyst 102 pellet diameters. Inone embodiment, the ratio of pellet diameter (d) to cross sectionalheight 117 (D) may range from about 0.0125 to about 1. A D/d ratio fromabout 5 to about 20 is also suitable for many applications. A packingdensity may also characterize packing of catalyst 102 in reformerchamber 103. For a copper zinc catalyst 102, packing densities fromabout 0.3 grams/milliliter to about 2 grams/milliliter are suitable.Packing densities from about 0.9 grams/milliliter to about 1.4grams/milliliter are appropriate for the embodiment shown in FIG. 3A.

One suitable catalyst 102 may include CuZn on alumina pellets whenmethanol is used as a hydrocarbon fuel source 17. Other materialssuitable for catalyst 102 may be based on nickel, platinum, palladium,or other precious metal catalysts either alone or in combination, forexample. Catalyst 102 pellets are commercially available from a numberof vendors known to those of skill in the art. Pellet catalysts may alsobe disposed within a baffling system disposed in the reformer chamber103. The baffling system includes a set of walls that guide the fuelsource along a non-linear path. The baffling slows and controls flow ofgaseous methanol in chamber 103 to improve interaction between thegaseous methanol and pellet catalyst 102. Catalyst 102 may alternativelycomprise catalyst materials listed above coated onto a metal sponge ormetal foam. A wash coat of the desired metal catalyst material onto thewalls of reformer chamber 103 may also be used for reformer 32.

Reformer 32 is configured to output hydrogen and includes an outlet port87 that communicates hydrogen formed in reformer 32 outside of fuelprocessor 15. In fuel cell system 10, port 87 communicates hydrogen toline 39 for provision to hydrogen distribution 43 in fuel cell 20. Port87 is disposed on a wall of end plate 82 and includes a hole that passesthrough the wall (see FIG. 2B). The outlet hole port may be disposed onany suitable wall 111 or 113.

Hydrogen production in reformer 32 is slightly endothermic and drawsheat from burner 30. Burner 30 generates heat and is configured toprovide heat to reformer 32. Burner 30 is disposed annularly aboutreformer 32, as will be discussed in further detail below. As shown inFIG. 2B, burner 30 comprises two burners (or burner sections) 30 a and30 b and their respective burner chambers 105 a and 105 b that surroundreformer 32. Burner 30 includes an inlet that receives methanol 17 fromboiler 108 via a channel in one of end plates 82 or 84. In oneembodiment, the burner inlet opens into burner chamber 105 a. Themethanol then travels the length 142 of burner chamber 105 a to channelsdisposed in end plate 82 that route methanol from burner chamber 105 ato burner chamber 105 b. The methanol then travels the back through thelength 142 of burner chamber 105 b to burner exhaust 89. In anotherembodiment, the burner inlet opens into both chambers 105 a and 105 b.The methanol then travels the length 142 of both chambers 105 a and 105b to burner exhaust 89.

In one embodiment, burner 30 employs catalytic combustion to produceheat. A catalyst 104 disposed in each burner chamber 105 helps a burnerfuel passed through the chamber generate heat. In one embodiment,methanol produces heat in burner 30 and catalyst 104 facilitates themethanol production of heat. In another embodiment, waste hydrogen fromfuel cell 20 produces heat in the presence of catalyst 104. Suitableburner catalysts 104 may include platinum or palladium coated onto asuitable support or alumina pellets for example. Other materialssuitable for catalyst 104 include iron, tin oxide, other noble-metalcatalysts, reducible oxides, and mixtures thereof. The catalyst 104 iscommercially available from a number of vendors known to those of skillin the art as small pellets. The pellets that may be packed into burnerchamber 105 to form a porous bed or otherwise suitably filled into theburner chamber volume. Catalyst 104 pellet sizes may be varied relativeto the cross sectional size of burner chamber 105. Catalyst 104 may alsocomprise catalyst materials listed above coated onto a metal sponge ormetal foam or wash coated onto the walls of burner chamber 105. A burneroutlet port 89 (FIG. 2A) communicates exhaust formed in burner 30outside of fuel processor 15.

Some fuel sources generate additional heat in burner 30, or generateheat more efficiently, with elevated temperatures. Fuel processor 15includes a boiler 108 that heats methanol before burner 30 receives thefuel source. In this case, boiler 108 receives the methanol via fuelsource inlet 85. Boiler 108 is disposed in proximity to burner 30 toreceive heat generated in burner 30. The heat transfers via conductionthrough monolithic structure from burner 30 to boiler 108 and viaconvection from boiler 108 walls to the methanol passing therethrough.

Air including oxygen enters fuel processor 15 via air inlet port 91.Burner 30 uses the oxygen for catalytic combustion of methanol. As willbe discussed in further detail below with respect to FIGS. 4A and 4B,air first passes along the outside of dewar 150 before passing throughapertures in the dewar and along the inside of dewar 150. This heats theair before receipt by air inlet port 93 of burner 30.

FIG. 3A illustrates a cross-sectional front view of monolithic structure100 as taken through a mid-plane 121 in accordance with one embodimentof the present invention. Monolithic structure 100 extends from endplate 82 to end plate 84. The cross section of monolithic structure 100shown in FIG. 3A extends from one end of structure 100 at end plate 82to the other end of structure 100 at end plate 84. Monolithic structure100 includes reformer 32, burner 30, boiler 34 and boiler 108 betweenend plates 82 and 84.

Reformer 32 includes a reformer chamber 103, which is a voluminous spacein fuel processor 15 that includes the reforming catalyst 102, opens tothe fuel source inlet (from boiler 34 for fuel processor 15), and opensto hydrogen outlet 87. Side walls 111 define a non-planarcross-sectional shape for reformer 32 and its reformer chamber 103.Walls 113 on end plates 82 and 84 close the reformer chamber 103 oneither end of the chamber 103 and include the inlet and outlet ports tothe chamber 103.

Reformer chamber 103 includes a non-planar volume. As the term is usedherein, a non-planar reformer chamber 103 refers to a shape in crosssection that is substantially non-flat or non-linear. A cross sectionrefers to a planar slice that cuts through the fuel processor orcomponent. For cross sections that include multiple fuel processorcomponents (e.g., both burner 30 and reformer 32), the cross sectionincludes both components. For the vertical and front cross section 121shown in FIG. 3A, the cross section dimensions shown are consistent formonolithic structure 100 from end plate 82 to end plate 84, and areconsistent at each cross section 121 (FIG. 2A).

Reformer 32 and its reformer chamber 103 may employ a quadrilateral ornon-quadrilateral cross-sectional shape. Four sides define aquadrilateral reformer chamber 103 in cross section. Four substantiallyorthogonal sides define rectangular and square quadrilateral reformers32. A non-quadrilateral reformer 32 may employ cross-sectionalgeometries with more or less sides, an elliptical shape (see FIG. 3B),and more complex cross-sectional shapes. As shown in FIG. 3A, reformer32 includes a six-sided cross-sectional ‘P-shape’ with chamferedcorners. One corner section of reformer 32 is removed from monolithicstructure 100 to allow for boiler 34 proximity to burner 30.

Reformer chamber 103 is characterized by a cross-sectional width 115 anda cross-sectional height 117. A maximum linear distance between innerwalls 111 of chamber 103 in a direction spanning a cross section ofreformer chamber 103 quantifies cross-sectional width 155. A maximumlinear distance between inner walls 111 of chamber 103 orthogonal to thewidth 115 quantifies cross-sectional height 117. As shown,cross-sectional height 117 is greater than one-third the cross-sectionalwidth 115. This height/width relationship increases the volume ofreformer chamber 103 for a given fuel processor 15. In one embodiment,cross-sectional height 117 is greater than one-half cross-sectionalwidth 115. In another embodiment, cross-sectional height 117 is greaterthan the cross-sectional width 115.

Referring back to FIG. 2A, reformer chamber 103 includes a length 142(orthogonal to the width 115 and height 117) that extends from one endof monolithic structure 100 at end plate 82 to the other end ofstructure 100 at end plate 84. In one embodiment, reformer chamber 103has a length 142 to width 115 ratio less than 20:1. In a less elongateddesign, reformer chamber 103 has a length 142 to width 115 ratio lessthan 10:1.

Reformer 32 provides a voluminous reformer chamber 103. This threedimensional configuration for reformer chamber 103 contrasts micro fuelprocessor designs where the reformer chamber is etched as micro channelsonto a planar substrate. The non-planar dimensions of reformer chamber103 permit greater volumes for reformer 32 and permit more catalyst 102for a given size of fuel processor 15. This increases the amount ofmethanol that can be processed and increases hydrogen output for aparticular fuel processor 15 size. Reformer 32 thus improves fuelprocessor's 15 suitability and performance in portable applicationswhere fuel processor size is important or limited. In other words, sincethe size of inlet and outlet plumbing and ports varies little whileincreasing the reformer chamber 103 volume, this allows fuel processor15 to increase hydrogen output and increase power density for portableapplications while maintaining size and weight of the associatedplumbing relatively constant. In one embodiment, reformer chamber 103comprises a volume greater than about 0.1 cubic centimeters and lessthan about 50 cubic centimeters. In some embodiments, reformer 32volumes between about 0.5 cubic centimeters and about 2.5 cubiccentimeters are suitable for laptop computer applications.

Fuel processor 15 includes at least one burner 30. Each burner 30includes a burner chamber 105. For a catalytic burner 30, the burnerchamber 105 is a voluminous space in fuel processor 15 that includescatalyst 104. For communication or burner reactants and products to andfrom the burner chamber 105, the burner chamber 105 may directly orindirectly open to a fuel source inlet (from boiler 108 for fuelprocessor 15), open to an air inlet 93, and open to a burner exhaust 89.

The number of burners 30 and burner chambers 105 may vary with design.Monolithic structure 100 of FIG. 3A includes a dual burner 30 a and 30 bdesign having two burner chambers 105 a and 105 b, respectively, formingnon-continuous chambers that substantially surround reformer 32 in crosssection. Burner 30 a comprises side walls 119 a (FIG. 3A) included inmonolithic structure 100 and end walls 113 on end plates 82 and 84 (FIG.2B) that define burner chamber 105 a. Similarly, burner 30 b includesside walls 119 b (FIG. 3A) included in monolithic structure 100 and endwalls 113 on end plates 82 and 84 (FIG. 2B) that define burner chamber105 b. Monolithic structure 100 of FIG. 3C includes a single burner 30 cwith a single burner chamber 105 c that fully surrounds reformer 32.Tubular arrangement of FIG. 3B includes over forty burners 204 thatfully surround reformer 202. Monolithic structure 452 of FIG. 4Fincludes a single burner divided into 104 burner chambers that fullysurround reformer 32.

Referring to FIG. 2B, each burner 30 is configured relative to reformer32 such that heat generated in a burner 30 transfers to reformer 32. Inone embodiment, the one or more burners 30 are annularly disposed aboutreformer 32. As the term is used herein, annular configuration of atleast one burner 30 relative to reformer 32 refers to the burner 30having, made up of, or formed by, continuous or non-continuous segmentsor chambers 105 that surround reformer 32. The annular relationship isapparent in cross section. For burner and reformer arrangements,surrounding refers to a burner 30 bordering or neighboring the perimeterof reformer 32 such that heat may travel from a burner 30 to thereformer 32. Burners 30 a and 30 b may surround reformer 32 about theperimeter of reformer 32 to varying degrees based on design. At theleast, one or more burners 30 surround greater than 50 percent of thereformer 32 cross-sectional perimeter. This differentiates fuelprocessor 15 from planar and plate designs where the burner and reformerare co-planar and of similar dimensions, and by geometric logic, theburner neighbors less than 50 percent of the reformer perimeter. In oneembodiment, one or more burners 30 surround greater than 75 percent ofthe reformer 32 cross-sectional perimeter. Increasing the extent towhich burner 30 surrounds reformer 32 perimeter in cross sectionincreases the surface area of reformer 32 that can be used to heat thereformer volume via heat generated in the burner. For some fuelprocessor 15 designs, one or more burners 30 may surround greater than90 percent of the reformer 32 cross-sectional perimeter. For theembodiment shown in FIG. 3B, burner 30 surrounds the entire reformer 32cross-sectional perimeter.

Although the present invention will now be described with respect toburner 30 annularly disposed about reformer 32, it is understood thatmonolithic structure 100 may comprise the reverse configuration. Thatis, reformer 32 may be annularly disposed about burner 30. In this case,reformer 32 may comprise one or more continuous or non-continuoussegments or chambers 103 that surround burner 30.

In one embodiment, each burner 30 and its burner chamber 105 has anon-planar cross-sectional shape. A non-planar burner 30 may employcross-sectional shapes such as quadrilaterals, non-quadrilateralgeometries with more or less sides, an elliptical shape (see FIG. 3B forcircular/tubular burners 30), or more complex cross-sectional shapes. Asshown in FIG. 3A, each burner 30 includes a six-sided cross-sectional‘L’ shape (with chamfered corners) that bends 90 degrees about reformer32.

Each burner 30 thus bilaterally borders reformer 32. N-lateral borderingin this sense refers to the number of sides, N, of reformer 32 that aburner 30 (and its burner chamber 105) borders in cross section. Thus,burner 30 b borders the right and bottom sides of reformer 32, whileburner 30 a borders the top and left sides of reformer 32. A ‘U-shaped’burner 30 may be employed to trilaterally border reformer 32 on threesides. Together, burners 30 a and 30 b quadrilaterally border reformer32 on all four orthogonal reformer 32 sides. The reformer 32 used in theconfiguration of FIG. 3B includes multiple tubular burners thatquadrilaterally border reformer 32. FIG. 3C illustrates across-sectional front view of monolithic structure 100 that comprises asingle burner 30 c having an ‘O-shape’ that completely surroundsreformer chamber 103 in accordance with one embodiment of the presentinvention. Burner 30 c is a continuous chamber about the perimeter ofreformer 32 and quadrilaterally borders reformer 32.

Heat generated in burner 30 transfers directly and/or indirectly toreformer 32. For the monolithic structure 100 of FIG. 3A, each burner 30and reformer 32 share common walls 120 and 122 and heat generated ineach burner 30 transfers directly to reformer 32 via conductive heattransfer through common walls 120 and 122. Wall 120 forms a boundarywall for burner 30 b and a boundary wall for reformer 32. As shown, oneside of wall 120 opens to burner chamber 105 b while another portion ofthe wall opens to reformer chamber 103. Wall 120 thus permits directconductive heat transfer between burner 30 b and reformer 32. Similarly,wall 122 forms a boundary wall for burner 30 a and a boundary wall forreformer 32, opens to burner chamber 105 a, opens to reformer chamber103, and permits direct conductive heat transfer between burner 30 a andreformer 32. Walls 120 and 122 are both non-planar in cross section andborder multiple sides of reformer chamber 103 that are neighbored byburners 30 b and 30 a. Wall 120 thus provides direct conductive heattransfer in multiple orthogonal directions 128 and 129 from burner 30 ato reformer 32. Wall 122 similarly provides direct conductive heattransfer in directions opposite to 128 and 129 from burner 30 b toreformer 32.

Boiler 34 comprises cylindrical walls 143 included in monolithicstructure 100 and end walls 113 on end plates 82 and 84 (see FIG. 2B)that define boiler chamber 147. Circular walls 143 in cross section forma cylindrical shape for boiler 34 that extends from routing end 82 torouting end 84. Boiler 34 is disposed in proximity to burners 30 a and30 b to receive heat generated in each burner 30. For monolithicstructure 100, boiler 34 shares a common wall 130 with burner 30 a and acommon wall 132 with burner 30 b. Common walls 130 and 132 permit directconductive heat transfer from each burner 30 to boiler 34. Boiler 34 isalso disposed between burners 30 and reformer 32 to intercept thermalconduction consistently moving from the high temperature and heatgenerating burners 30 to the endothermic reformer 32.

Boiler 108 is configured to receive heat from burner 30 to heat methanolbefore burner 30 receives the methanol. Boiler 108 also comprises atubular shape having a circular cross section that extends throughmonolithic structure 100 from end plate 82 to end plate 84. Boiler 108is disposed in proximity to burners 30 a and 30 b to receive heatgenerated in each burner 30, which is used to heat the methanol. Boiler108 shares a common wall 134 with burner 30 a and a common wall 136 withburner 30 b. Common walls 134 and 136 permit direct conductive heattransfer from burners 30 a and 30 b to boiler 108.

FIG. 3D illustrates an outside view of end plate 82 in accordance withone embodiment of the present invention. End plate 82 includes fuelsource inlet 81, fuel source fuel source inlet 85, hydrogen outlet port87 and burner air inlet 93. Fuel source inlet 81 includes a hole or portin end wall 113 of end plate 82 that communicates methanol (usually as aliquid) from an external methanol supply to boiler 34 for heating themethanol before receipt by reformer 32. Methanol fuel source inlet 85includes a hole or port in end wall 113 of end plate 82 thatcommunicates methanol (usually as a liquid) from an external methanolsupply to boiler 108 for heating the methanol before receipt by burner30. Burner air inlet 93 includes a hole or port in end wall 113 of endplate 82 that communicates air and oxygen from the ambient room after ithas been preheated in dewar 150. Hydrogen outlet port 87 communicatesgaseous hydrogen from reforming chamber 103 outside fuel processor 15.

Bolt holes 153 are disposed in wings 145 of monolithic structure 100.Bolt holes 153 permit the passage of bolts therethrough and allowsecuring of structure 100 and end plates 82 and 84.

FIG. 3B illustrates a cross-sectional layout of a tubular design 200 foruse in fuel processor 15 in place of monolithic structure 100 inaccordance with another embodiment of the present invention. Structure200 includes a reformer 202, burner 204, boiler 206 and boiler 208.

The cross-sectional design 200 shown in FIG. 3B is consistent throughouta cylindrical length between end plates (not shown) that include inletand outlet ports for supply and exhaust of gases to components of design200. The circular shape of reformer 202, burner chambers 212, boiler 206and boiler 208 thus extends for the entire cylindrical length betweenthe end plates. The end plates may also be responsible for routing gasesbetween individual tubes, such as between tubular burners 234.

Reformer 202 includes cylindrical walls 203 that define a substantiallycircular cross section. Reformer 232 thus resembles a hollow cylinder inthree dimensions that defines a tubular reformer chamber 210. Ingeneral, reformer 202 may include any elliptical shape (a circlerepresents an ellipse of about equal orthogonal dimensions) suitable forcontaining the catalyst 102, for methanol flow through reformer chamber210, for hydrogen production in reformer chamber 210, and for hydrogenflow in reformer chamber 210. As shown, reformer chamber 210 is definedby a cross sectional width and a cross sectional height that aresubstantially equal and thus reformer 202 includes a 1:1 cross sectionalaspect ratio.

Burner 204 comprises a set of cylindrical walls 214 that each defines atubular burner chamber 212. As shown, tubular design 200 includes overforty tubular burner chambers 212 that fully surround the crosssectional perimeter of reformer 32. Each tubular burner chamber 212includes a substantially circular cross-section defined by thecylindrical wall 214. Each tubular burner chamber 212 includes catalyst104 that facilitates heat generation from methanol. Burner 204 maycomprise from about two to about two hundred cylindrical walls 214 andtubular burner chambers 212. Some designs may include from about ten toabout sixty tubular burner chambers 212. In one embodiment, eachcylindrical wall 214 comprises a metal and is extruded to its desireddimensions. In a specific embodiment, cylindrical wall 214 comprisesnickel. The nickel wall 214 may be formed by electroplating nickel ontoa suitable substrate such as zinc or aluminum that may subsequentlyetched out to leave the nickel tube. Other materials that a nickel wall214 may be formed onto include zinc, tin, lead, wax or plastics. Inaddition to nickel, wall 214 may include gold, silver, copper, stainlesssteel, ceramics and materials that display suitable thermal propertieswithout causing complications with burner catalyst 104.

As shown, burner 204 fully annularly surrounds the cross-sectionalperimeter of reformer 202. In this case, burner 204 comprises threering-like layers 216, 218 and 220 of tubes 214 disposed circularly aboutreformer 202 and at three different radii. The tubes 214 in each layer216, 218 and 220 circumscribe reformer 202. Heat generated in eachtubular chamber 212 of burner 30 transfers directly or indirectly toreformer 202 via several paths: a) heat conduction through the tubes 214in layer 216 to the walls of reformer 202; b) heat conduction throughthe tubes 214 in outer layers 218 and 220 to tubes 214 in layer 216 andto the walls of reformer 202; and/or c) heat radiation between tubes 214in outer layers 218 and 220 and tubes 214 and then conduction inward toreformer 202.

Boiler 206 is configured to heat methanol before reformer 202 receivesthe methanol. Boiler 206 receives heat from burner 204 and comprises acylindrical wall 207 that defines a tubular shape for the boiler. Boiler206 is disposed in proximity to burner tubes 214 to receive heatgenerated in each burner chamber 212. Specifically, boiler 206 isdisposed in the second ring-like layer 218 and receives heat fromadjacent burner chambers 212 in layers 216, 218 and 220. Burner 204provides heat to boiler 206 via conduction through the walls of eachadjacent tube 214 and through wall 207.

Boiler 208 is configured to heat methanol before burner 204 receives themethanol. Boiler 208 receives heat from burner 204 and also comprises acylindrical wall 209 that defines a tubular shape for the boiler.Similar to boiler 206, boiler 208 is disposed in the second ring-likelayer 218 and receives heat from adjacent burner chambers 212 in layers216, 218 and 220.

In one embodiment, a monolithic fuel processor 15 comprises multiplesegments joined together in the direction of gas flow in reformerchamber 103 and joined at sectional lines 121. Each segment has a commonprofile as shown in FIG. 3A and may comprise metal or ceramic elementsthat are bonded or brazed perpendicular to the direction of gas flow.Alternatively, fuel processor 15 may comprise a single long monolithicpiece that bounds all of reformer 32, burner 30, boiler 34 and boiler108 except for areas bound by end pieces 82 and 84.

In another embodiment, fuel processor 15 comprises multiple piecesjoined together in cross section. FIG. 3E illustrates a fuel processor15 in accordance with another embodiment of the present invention. Inthis case, fuel processor 15 comprises three pieces: lower piece 280,middle piece 282 and cap piece 284. Lower piece 280 and middle piece 282attach to form reformer 32 and two burner chambers 30. Cap piece 284 andmiddle piece 282 attach to form boilers 34 and 108. Each piece 208, 282and 284 comprises a common material and may be extruded or cast tosuitable dimensions. Attachment between the pieces may comprise chemicalbonding, for example.

FIG. 4A illustrates a side cross-sectional view of fuel processor 15 andmovement of air created by dewar 150 in accordance with one embodimentof the present invention. FIG. 4B illustrates a front cross-sectionalview of fuel processor 15 and demonstrates thermal management benefitsgained by dewar 150. While thermal management techniques describedherein will now be described as fuel processor components, those skilledin the art will recognize that the present invention encompasses methodsof thermal management for general application.

A burner 30 in fuel processor 15 generates heat and typically operatesat an elevated temperature. Burner 30 operating temperatures greaterthan 200 degrees Celsius are common. Standards for the manufacture ofelectronics devices typically dictate a maximum surface temperature fora device. Electronics devices such as laptop computers often includecooling, such as a fan or cooling pipe, to manage and dissipate internalheat. A fuel processor internal to an electronics device that loses heatinto the device calls upon the device's cooling system to handle thelost heat.

In one embodiment, fuel processor 15 comprises a dewar 150 to improvethermal management for fuel processor 15. Dewar 150 at least partiallythermally isolates components internal to housing 152—such as burner30—and contains heat within fuel processor 15. Dewar 150 reduces heatloss from fuel processor 15 and helps manage the temperature gradientbetween burner 30 and outer surface of housing 152. And as will bedescribed below, dewar 150 also pre-heats air before it is received byburner 30.

Dewar 150 at least partially contains burner 30 and reformer 32, andincludes a set of dewar walls 154 that help form a dewar chamber 156 anda chamber 158. In some embodiments, dewar 150 fully surrounds burner 30and reformer 32 in a cross sectional view and at both ends of burner 30and reformer 32. Less containment by dewar 150 is also suitable toprovide thermal benefits described herein. The multipass dewar 300 ofFIG. 4E only partially encloses burner 30 and reformer 32 in crosssection. In some cases, dewar 150 does not extends fully along thelength of monolithic structure 100 and provides less than fullcontainment.

As shown in FIG. 4B, dewar 150 annularly surrounds burner 30 in crosssection. The set of walls 154 includes side walls 154 a and 154 c thatcombine with top and bottom walls 154 b and 154 d to form therectangular cross section shown in FIG. 4B; and includes two end walls154 e and 154 f that combine with top and bottom walls 154 b and 154 dto form the rectangular cross section shown in FIG. 4A. End wall 154 fincludes apertures that permit the passage of inlet and outlet ports 85,87 and 89 therethough.

Dewar chamber 156 is formed within dewar walls 154 and comprises allspace within the dewar walls 154 not occupied by monolithic structure100. As shown in FIG. 4B, dewar chamber 156 surrounds monolithicstructure 100. As shown in FIG. 4B, chamber 156 comprises ducts betweenmonolithic structure 100 and walls 154 on all four sides of dewar 150.In addition, chamber 156 comprises air pockets between end walls ofdewar 150 and outside surfaces of end plates 82 and 84 on both ends ofmonolithic structure 100 (FIG. 4A).

Chamber 158 is formed outside dewar walls 154 between dewar 150 andhousing 152. Chamber 158 comprises all space within housing 152 notoccupied by dewar 150. As shown in FIG. 4B, housing 152 encloses dewar150 and the further internal monolithic structure 100. Chamber 158comprises ducts between walls 154 on all four sides of dewar 150 andhousing 152. In addition, chamber 158 comprises air pockets 167 betweendewar 150 and housing 152 on both ends that prevent contact andconductive heat transfer between dewar 150 and housing 152 (FIG. 4A).

Dewar 150 is configured such that a process gas or liquid passingthrough dewar chamber 156 receives heat generated in burner 30. Theprocess gas or liquid may include any reactant used in fuel processorsuch as oxygen, air, or fuel source 17, for example. Dewar 150 offersthus two functions for fuel processor 15: a) it permits active coolingof components within fuel processor 15 before the heat reaches an outerportion of the fuel processor, and b) it pre-heats the air going toburner 30. For the former, air moves through fuel processor 15 andacross walls 154 of dewar 150 such that the cooler air absorbs heat fromthe warmer fuel processor 15 components.

As shown in FIG. 4A, housing 152 includes an air inlet port 91 or holethat permits the passage of air from outside housing 152 into air intochamber 158. A fan usually provides the air directly to fuel processor15 and pressurizes the air coming through port 91. Top and bottom walls154 b and 154 d include air inlet ports or holes 172 that allow air topass from chamber 158 to dewar chamber 156. Air flow through fuelprocessor 15 then flows: in air inlet port 91, through chamber 158 alongthe length of the dewar 150, through holes 172 in walls 154 b and 154 d,through chamber 156 back along the length of the dewar 150 in theopposite direction as in through chamber 158, and into air inlet ports176 that allow the air to enter burner 30. In chamber 158, the air a)moves across the outside surface of dewar walls 154 and absorbs heatconvectively from dewar walls 154, and b) moves across the insidesurface of housing 152 and absorbs heat convectively from the housing152 walls (when housing 152 is at a greater temperature than the air).In chamber 156, the air a) moves across the outside surface ofmonolithic structure 100 and absorbs heat convectively from the walls ofmonolithic structure 100, and b) moves across the inside surface ofdewar 150 and absorbs heat convectively from dewar walls 154.

Dewar 150 is thus configured such that air passing through the dewarreceives heat generated in burner 30 via direct convective heat transferfrom walls in monolithic structure 100 on the outside of burner 30 toair passing through dewar chamber 156. Dewar 150 is also configured tosuch that air passing through chamber 156 receives heat indirectly fromburner 30. Indirectly in this sense refers to heat generated in burner30 moving to another structure in fuel processor 15 before receipt bythe air.

FIG. 4C illustrates a thermal diagram of the heat path produced by awall 154 of dewar 150. Heat from burner 30 conducts through monolithicstructure 100 to a surface of structure 100 that opens into dewarchamber 156. From here, the heat a) conducts into the air passingthrough dewar chamber 156, thereby heating the air; b) radiates to theinner wall 155 of dewar wall 154, from which the heat convects into theair passing through dewar chamber 156; c) radiates to the inner wall 155of dewar wall 154, conducts through wall 154 to the outer surface 157 ofdewar wall 154, from which the heat convects into the air passingthrough dewar chamber 158, and d) radiates to the inner wall 155 ofdewar wall 154, conducts through wall 154 to the outer surface 157 ofdewar wall 154, radiates to a wall of housing 152, from which the heatconvects into the air passing through dewar chamber 158.

Dewar 150 thus provides two streams of convective heat dissipation andactive air-cooling in volumes 156 and 158 that prevent heat generated inburner 30 (or other internal parts of fuel processor 15) from escapingthe fuel processor.

Reflectance of heat back into chamber 156 decreases the amount of heatlost from fuel processor 150 and increases the heating of air passingthrough chamber 156. To further improve the radiative reflectance backinto chamber 156, an inside surface of dewar wall 154 may include aradiative layer 160 to decrease radiative heat transfer into wall 154(see FIG. 4B or 4C). Radiative layer 160 is disposed on an inner surface155 on one or more of walls 154 to increase radiative heat reflectanceof the inner surface 155. Generally, the material used in radiativelayer 160 has a lower emissivity than the material used in walls 154.Materials suitable for use with walls 154 of dewar 150 include nickel ora ceramic, for example. Radiative layer 160 may comprise gold, platinum,silver, palladium, nickel and the metal may be sputter coated onto theinner surface 155. Radiative layer 160 may also include a low heatconductance. In this case, radiative layer 160 may comprise a ceramic,for example.

When dewar 150 fully encapsulates monolithic structure 100, the dewarthen bounds heat loss from the structure and decreases the amount ofheat passing out of dewar 150 and housing 152. Fuel processors 15 suchas that shown in FIGS. 4A and 4B are well suited to contain heat withinhousing 152 and manage heat transfer from the fuel processor. In oneembodiment, burner operates at a temperature greater than about 200degrees Celsius and the outer side of the housing remains less thanabout 50 degrees Celsius. In embodiments for portable applications wherefuel processor 15 occupies a small volume, volumes 156 and 158 arerelatively small and comprise narrow channels and ducts. In some cases,the height of channels in volumes 156 and 158 is less than 5 millimetersand a wall of burner 30 on monolithic structure is no greater than 10millimeters from a wall of housing 152.

The thermal benefits gained by use of dewar 150 also permit the use ofhigher temperature burning fuels as a fuel source for hydrogenproduction, such as ethanol and gasoline. In one embodiment, the thermalmanagement benefits gained by use of dewar 150 permit reformer 32 toprocess methanol at temperatures well above 100 degrees Celsius and attemperatures high enough that carbon monoxide production in reformer 32drops to an amount such that a preferential oxidizer is not needed.

As mentioned above, dewar 150 offers a second function for fuelprocessor 15 by pre-heating the air going to a burner. Burner 30 relieson catalytic combustion to produce heat. Oxygen in the air provided toburner 30 is consumed as part of the combustion process. Heat generatedin the burner 30 will heat cool incoming air, depending on thetemperature of the air. This heat loss to incoming cool air reduces theheating efficiency of burner 30, and typically results in a greaterconsumption of methanol. To increase the heating efficiency of burner30, the present invention heats the incoming air so less heat generatedin the burner passes into the incoming air. In other words, chambers andair flow formed by dewar 150 allow waste heat from the burner topre-heat air before reaching the burner, thus acting as a regeneratorfor fuel cell 15.

While fuel processor 15 of FIGS. 4A and 4B shows dewar 150 encapsulatingmonolithic structure 100, the present invention may also employ otherarchitectures for dewar 150 and relationships between burner 30 orreformer 32 and dewar 150 that carry out one or both of the dewarfunctions described above. FIG. 4D illustrates a cross sectional view ofa fuel processor 15 that elongates the convective path for cool air flowover a warmer dewar wall 254 in accordance with another embodiment ofthe present invention. Fuel processor 15 includes a tubular design forthe burner 30 and reformer 32.

Dewar 250 routes cool incoming air across an elongated heat transferpath. Dewar 250 includes a spiral wall 254 in cross section thatsurrounds burner 30 and reformer 32. Spiral wall 254 defines a spiraldewar chamber 256. Cool air enters dewar chamber 256 at a dewar entrance252. The innermost portion 257 of wall 254 attaches to an outer wall 258of burner 30. Heat from burner 30 conducts linearly through spiral wall254. Thus, inner portion 257 is the warmest portion of wall 254, whilewall 254 at entrance 252 is typically the coolest. Air progressivelywarms as it travels through dewar chamber 256. As the air travelsinward, temperature of wall 254 rises, as does the amount of heatavailable for transfer to the air. Depending on the transienttemperature of the air, the amount of heat lost from wall 154 may alsoincrease as the air progresses inward.

Spiral dewar 250 elongates convection interaction between the incomingcool air and a wall warmed by the burner. Dewar 250 also increases thenumber of walls and convective layers in a given radial direction fromthe fuel processor center. As shown in FIG. 4D, dewar 250 comprises 4-5walls and convective layers in a given radial direction, depending onwhere the number is counted. The number of walls and convective in aradial direction may vary with design. In one embodiment, spiral dewar250 is configured with from 1 layer to about 50 walls and convectivelayers in a given radial direction from the fuel processor center. Threelayers to 20 layers are suitable for many applications. A channel width260 defines the duct space between adjacent walls 254. In oneembodiment, channel width 260 ranges from about ¼ millimeters to about 5millimeters.

Spiral dewar 250 may be constructed by electroplating nickel onto aremovable layer such as aluminum or zinc. FIG. 4H illustrates spiraldewar 250 in an unrolled form during initial construction in accordancewith another embodiment of the present invention. Initial aluminum orzinc layer 262 is added to control channel width 260 during rolling. Theremovable layer 262 is subsequently electroplated with the wall 214choice of material, for example nickel. After which the aluminum or zinclayer is etched out employing an electroforming technique thus leaving aspiral dewar 250.

The spiral dewar 250 shown in FIG. 4H also employs an embossed or foldedburner structure 264 that wraps around reformer 32. FIGS. 4I and 4Jillustrate wash coatings 266 on a wall 268 of burner 30 in accordancewith two embodiments of the present invention. For the folded burnerstructure 264 of FIG. 4I, a wash coat 266 including the burner catalyst104 is applied to both sides of wall 268.

A flat wall 270 suitable for use in spiral dewar 250 is shown in FIG.4J. Flat wall 270 includes channels 272 etched or otherwise disposedalong its surface. A wash coat 266 including the burner catalyst 104 isthen added over the surface of flat wall 270 and channels 272.

Fuel processors 15 such as that shown in FIG. 4D are very well suited tocontain internally generated heat. In one embodiment, burner 30 operatesat a temperature greater than about 350 degrees Celsius and the outerside of the housing remains less than about 75 degrees Celsius. Thisfacilitates the use of higher temperature burning fuel sources withinburner 30 such as ethanol and propane, for example.

Dewars as shown in FIGS. 4A and 4D may be considered ‘multipass’ sincethe incoming air passes over multiple surfaces for convective heattransfer between the warmer surfaces and cooler air. The embodiment inFIG. 4A illustrates a two-pass system where the air passes through twodewar chambers, while the embodiment in FIG. 4D illustrates an N-passwhere N is the number of dewar walls in a given radial direction fromthe fuel processor center.

FIG. 4E illustrates a cross sectional view of a multipass dewar 300 inaccordance with another embodiment of the present invention. Dewar 300comprises four dewar walls 302 a-d that connect to a housing wall 304.Dewar 300 partially contains monolithic structure 100. Dewar wall 302 acooperates with housing wall 304 to enclose monolithic structure 100,which includes burner 30. Dewar wall 302 b and housing wall 304 enclosedewar wall 302 a and burner 30. Similarly, dewar wall 302 c and housingwall 304 enclose dewar wall 302 b, while dewar wall 302 d and housingwall 304 enclose dewar wall 302 c. Dewar walls 302 a-d form four volumesfor incoming air to pass over warmer walls and receive heat. Air entersdewar inlet port 310 and flows through dewar chamber 308 a and intodewar chamber 308 b through port 312 after travelling throughsubstantially the whole chamber 308 a. Air then serially passes into andthrough chambers 308 c and 308 d before entering burner inlet 314.

FIGS. 4F and 4G illustrate a cross section of a fuel processor 15including a monolithic structure 452 and multipass dewar 450 inaccordance with another embodiment of the present invention. Monolithicstructure 452 includes multiple reformer chambers 454 that are disposedin a central portion of structure 452. Multiple burner chambers 456surround and quadrilaterally border the reformer chambers 454. Reformerboiler 458 is arranged within the cross section of burner chambers 456,while burner boiler 460 is arranged in external portion of the crosssection.

Dewar 462 comprises four dewar walls 462 a-d. In the cross section shownin FIG. 4F, dewar wall 462 a surrounds monolithic structure 452. Dewarwall 462 b surrounds and encloses dewar wall 462 a. Dewar wall 462 csurrounds and encloses dewar wall 462 b, while dewar wall 462 dsurrounds and encloses dewar wall 462 c. Dewar walls 462 a-d form fourdewar volumes for incoming air to pass through and receive heat. Asshown in FIG. 4G, air enters dewar inlet port 464 and flows throughdewar chamber 468 a and into dewar chamber 468 b after traveling throughsubstantially the whole chamber 468 a along the length of monolithicstructure 452. Air then serially passes from chamber 468 b to chamber468 c and chamber 468 d before entering burner inlet 470.

FIG. 5 illustrates a process flow 500 for generating hydrogen in a fuelprocessor in accordance with one embodiment of the present invention.The fuel processor comprises a burner, a reformer and a dewar that atleast partially contains the burner and reformer. Although the presentinvention has so far discussed dewars with respect to annular reformerand burner designs described herein, it is also anticipated that dewarsdescribed herein are also useful to contain heat in other reformer andburner designs. Many architectures employ a planar reformer disposed ontop or below to a planar burner. Micro-channel designs fabricated insilicon commonly employ such stacked planar architectures and wouldbenefit from dewars described herein.

Process flow 500 begins by generating heat in the burner (502).Catalytic burner architectures may include those described above or amicro-channel design on silicon. Further description of a micro-channelfuel processor suitable for use with the present invention is includedin commonly owned co-pending patent application entitled “Planar MicroFuel Processor” naming Ian Kaye as inventor and filed on the same day asthis patent application. This application is incorporated by referencefor all purposes. A catalyst in the burner facilitates heat generationin the presence of the heating fuel. The burner may also employ anelectric burner that includes an resistive heating element that producesheat in response to input current.

Air enters a port for the dewar and passes through a dewar chamber(504). For the dewar of FIG. 4A, burner 30 and dewar 150 share a walland the air passes through the dewar chamber 156 in a direction that atleast partially counters a direction that the air passes through burnerchamber 105.

The air is then heated in the dewar chamber using heat generated in theburner (506). Heat travels from burner 30 to dewar chamber 156 viaconductive heat transfer. Heat may also travel from a burner to a dewarchamber via convective and/or radiative heat transfer. Once in the dewarchamber, the air is typically heated via convective heat transfer from awall of the dewar to the air. In one embodiment, the dewar shares a wallwith the burner and air in the dewar chamber is heated using heat fromthe shared wall. Heat from the burner wall may also travel to otherwalls in the dewar and heat air in the dewar chamber after the heattransfers from the shared wall to another non-shared dewar wall. Heattraveling between the shared wall and non-shared dewar wall transfer byconduction between connected walls or radiation between facing walls.

Process flow 500 then supplies the warmed air to the burner after it hasbeen heated in the dewar chamber (508). Typically, the fuel processorincludes an exit to the dewar chamber and an inlet to the burner—alongwith any intermittent plumbing—that allow the heated air to passtherebetween. For the fuel processor shown in FIG. 2A, space betweendewar 150 and burner 30 at the ends of the burner route the air from thedewar to the burner.

The air is then used in the burner for catalytic combustion to generateheat. The generated heat is then transferred from the burner to thereformer (510). In the reformer, the heat is then used in reforming afuel source to produce hydrogen (512).

The first three elements (502, 504, and 506) of process flow 500 alsoform a method of managing heat in a fuel processor. In this case, heatgenerated in the burner (502) passes to air in the dewar (504). Thedewar 150 at least partially thermally isolates components internal tothe fuel processor housing—such as the burner—and contains heat withinthe fuel processor. The dewar thus reduces heat loss from the fuelprocessor and helps manage the temperature gradient between the burnerand outer surfaces of the housing. The dewar may also contain extendedand/or multiple dewar chambers through which the air passes and isheated by heat generated in the burner. FIG. 4A illustrates a seconddewar chamber 158 formed between the dewar and a housing for the fuelprocessor. Air passes first through chamber 158 then into dewar chamber156. FIG. 4D illustrates a spiral dewar including an extended dewarchamber 408. In this case, dewar 250 includes one wall that increasinglyprovides heat as incoming air nears the burner. FIG. 4E illustrates adewar 300 including four partially dewar chambers 308 where each dewarchamber heats incoming air in turn as it nears the burner. FIG. 4Fillustrates a dewar including four annular and concentric andrectangular dewar chambers 408 that each heat incoming air in turn as ittravels to the burner.

While this invention has been described in terms of several preferredembodiments, there are alterations, permutations, and equivalents thatfall within the scope of this invention which have been omitted forbrevity's sake. For example, although reformer 32 includes chamferedcorners as shown in FIG. 3A, the present invention may employnon-chamfered corners in reformer 32. In addition, although the presentinvention has been described in terms of a monolithic structure 100 thatforms the volumetric reformer 32, the present invention is not limitedto volumetric reformers disposed in monolithic structures. It istherefore intended that the scope of the invention should be determinedwith reference to the appended claims.

1. A fuel processor for producing hydrogen from a fuel source, the fuelprocessor comprising: a reformer including two or more reformer chambersin a cross section that are configured to receive the fuel source andconfigured to output hydrogen, each of the two or more reformer chambersincluding a reformer catalyst that facilitates the production ofhydrogen, wherein the two or more reformer chambers are configured suchthat reactants move through the two or more reformer chambers in series;a boiler configured to heat the fuel source before the reformer receivesthe fuel source; a burner including two or more burner chambers in across section, each of the two or more burner chambers including aburner catalyst, the two or more burner chambers configured to provideheat to the reformer, wherein the two or more burner chambers areconfigured such that reactants move through the two or more burnerchambers in series, wherein at least one of the burner chamberscomprises a wall shared by one of the two or more reformer chambers, thewall configured to permit conductive thermal communication therethroughfrom the burner catalyst to one of the two or more reformer chambers;and a dewar that at least partially contains the reformer, at leastpartially contains the burner and includes a set of dewar walls thatform a dewar chamber that is configured to receive the fuel source oroxygen before one of the two or more burner chambers receives the fuelsource or oxygen.
 2. The fuel processor of claim 1, wherein the dewarcomprises a shared wall between the dewar chamber and one of the burnerchambers, the shared wall configured to conductively transfer heat fromone of the burner chamber to the dewar chamber through the shared wall.3. The fuel processor of claim 1, further comprising a monolithicstructure having a common material included in walls that define the twoor more reformer chambers, the two or more burner chambers and theboiler, wherein the monolithic structure comprises the wall shared byone of the two or more reformer chambers and one of the two or moreburner chambers and the fuel processor.
 4. The fuel processor of claim3, wherein the monolithic structure is formed in a single extrusion orcasting.
 5. The fuel processor of claim 1, wherein the two or morereformer chambers surround greater than 50 percent of the two or moreburner chamber cross-sectional perimeter.
 6. The fuel processor of claim1, wherein the two or more burner chambers bilaterally neighbors the twoor more reformer chambers.
 7. The fuel processor of claim 1, wherein thetwo or more burner chambers each has a non-planar cross-sectional shape.8. The fuel processor of claim 1, wherein the dewar includes a radiativelayer disposed on an inner wall of the set of dewar walls that improvesradiative heat reflectance of the inner wall.
 9. The fuel processor ofclaim 1, wherein the dewar annularly surrounds the two or more burnerchambers in the cross section.
 10. The fuel processor of claim 1,wherein the dewar includes a second dewar chamber.
 11. A fuel processorfor producing hydrogen from a fuel source, the fuel processorcomprising: a reformer including two or more reformer chambers in across section that are configured to receive the fuel source andconfigured to output hydrogen, each of the two or more reformer chambersincluding a reformer catalyst that facilitates the production ofhydrogen, wherein the two or more reformer chambers are configured suchthat reactants move through the two or more reformer chambers in series;a boiler configured to heat the fuel source before the reformer receivesthe fuel source; a burner, including two or more burner chambers in across section, each of the two or more burner chambers include a burnercatalyst, each of the two or more burner chambers configured to provideheat to the reformer; a dewar that includes a set of dewar walls thatform a dewar chamber that is configured to receive the fuel source oroxygen before one of the two or more burner chambers receives the fuelsource or oxygen, wherein the dewar chamber comprises a shared wallbetween the dewar chamber and one of the burner chambers, the sharedwall configured to conductively transfer heat from one of the burnerchamber to the dewar chamber through the shared wall, wherein the fuelprocessor includes a monolithic structure comprising copper that forms awall of at least one of the two or more reformer chambers, a wall of atleast one of the two or more burner chambers, and a wall of the boiler.12. The fuel processor of claim 11, wherein the dewar contains thereformer and contains the burner, and the dewar chamber that isconfigured to receive the fuel source or oxygen before one of the two ormore burner chambers receives the fuel source or oxygen.
 13. The fuelprocessor of claim 11, wherein the two or more reformer chamberssurrounds greater than 50 percent of the two or more burner chambercross-sectional perimeter.
 14. The fuel processor of claim 11, whereinthe two or more reformer chambers surrounds greater than 75 percent ofthe two or more burner chamber cross-sectional perimeter.
 15. The fuelprocessor of claim 11, wherein the two or more burner chambers areconfigured such that reactants move through the two or more burnerchambers in series.
 16. The fuel processor claim 11, wherein themonolithic structure is formed in a single extrusion or casting.
 17. Thefuel processor of claim 11, wherein the burner is disposed annularlyabout the reformer.
 18. The fuel processor of claim 11, wherein theburner is configured to receive pre-heated gas or liquid directly fromthe dewar.
 19. The fuel processor of claim 18, wherein the dewar isconfigured to heat gas or liquid in the dewar chamber using heatgenerated in the burner and conductively transferred through the sharedwall.
 20. The fuel processor of claim 11, wherein the dewar annularlysurrounds the two or more burner chambers in the cross section.